Keeping insulation dry



March 28, 1967 v, SAUNDERS ET AL 3,310,957

KEEPING INSULATION DRY Filed Feb. 14, 1966 INVENTORS Orsqn V Saunderg BY LOUIS D Benasufll he' 'Afforn y United States .This invention pertains to household refrigerators and particularly to keeping dry the insulation under the bottom of drain pans in household refrigerators.

The insulating efiiciency of insulating material is substantially reduced by the presence of moisture and water which also frequently causes deterioration of the insulation material and damages the structure. In a refrigerator, moisture is often drawn into the insulation material by the presence of a cold surface in contact with it since moisture vapor migrates to the cold surface and freezes thereon. If the refrigerator is defrosted or shut down, the frozen liquid will melt from the cold surface and be driven into the insulation and cause a loss of insulating efliciency and possible damage to the structure of the insulating material.

It is an object of this invention to provide an arrange ment for preventing damage to the insulation and for preventing a reduction in the insulating efiiciency by preventing the collection of moisture frost and liquid upon a cold surface adjacent the insulation.

It is another object of this invention to provide an ar rangement wherein air from the duct containing the refrigerant evaporating means is positively circulated between the cold surface on which the moisture collects and the adjacent surface of the insulating material.

These and other objects are attained in the form shown in the drawings in which a horizontal dividing wall containing an evaporator in a duct and insulation divides the interior of the insulated cabinet into upper and lower subcompartments. The duct in this horizontal dividing wall has an air entrance at the front communicating with both sub-compartments. At the rear, this duct extends to the inlet of a centrifugal fan which discharges the air through upward and downward outlets back into both sub-compartments. A drain pan is provided beneath the evaporator which is spaced above the surface of the insulating material beneath it. The downward outlet of the fan is provided with a small discharge orifice and scoop for directing a portion of the air discharged downwardly from the fan into the air circulating space between the bottom of the drain pan and the surface of the insulating material beneath. This space between the drain pan and the insulating material communicates at the front with the front air entrance of the duct to provide for the forward circulation of air through this air circulating space. This circulation of air through this space between the drain pan and the surface of the insulating material prevents the collection of moisture vapor and the freezing of moisture upon the bottom of the drain pan so that when the refrigerator is defrosted or shut down there will be n water to drip on to the insulation. The circulation of air also prevents moisture from collecting on the surface of the insulation or soaking into the insulation. The bottom surface of the insulation is sealed by bonding thereto a metal sheet.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

The figure is a vertical sectional view through a household refrigerator cabinet embodying one form of our invention.

atent Patented Mar. 28, 1967 Referring now to the drawing, there is shown an insulated household refrigerator cabinet 20 provided with a horizontal partition wall 22 dividing the interior of the cabinet into upper and lower sub-compartments 24 and 26 surrounded by insulated cabinet walls. These-compartments are closed at the front by separate insulated doors 28 and 30. The horizontal partition wall includes a duct formed at the bottom by a drain pan 32 and at the top by a false sheet metal bottom wall 34 extending laterally to form the bottom of the upper sub-compartment 24. If desired, this bottom wall 34 may have a thin wedge-shaped sheet of polystyrene hollow bead insulation 36 on its under surface to prevent any collection of frost on the bottom wall 34. The duct so formed is provided with a cross-finned refrigerant evaporator 38 having refrigerant tubing extending horizontally from side to side and having vertical fins extending from the front to the rear. This duct is provided with upper front air entrances 40 communicating with the front of the upper sub-compartment 24 and a plurality of lower front air entrances 42 in the form and passages extending upwardly through the horizontal wall 22 into the space 44 in front of the evaporator 38. The horizontal partition wall 22 has a tongue 41 of insulation for directing the air entering from the upper and lower compartments 24 and 26 into the upper and lower parts of the space 44 in front of the evaporator 38 to minimize and distribute the deposit of frost on the front of the evaporator.

In such a refrigerator it is desirable to maintain a temperature of about 0 to 10 F. in the upper sub-compartment 24 and a temperature of about 35 to 40 in the lower sub-compartment 26. To attain this temperature in the upper sub-compartment 24 it is necessary to operate the refrigerant evaporator 38 at a temperature somewhat below the temperature desired in the sub-compartment 24, such as l0 to 15 F. Consequently, it is necessary to provide insulation material beneath the refrigerant evaporator 38 and the drain pan 32. However, moisture vapor tends to leak into the insulation material and be attracted to a cold surface on the under side of the drain pan 32. This moisture freezes onto this surface. When the refrigerator is shut down or defrosted, the drain pan 32 becomes warm enough to melt the frost and ice accumulated on the bottom face of the drain pan which will be driven as vapor and liquid into the insulation below and cause a loss of insulating efiiciency and possible damage to the structure of the insulating material. To prevent this, we provide an air circulating space 46 extending horizontally beneath the drain pan 32 and direcltly above the upper surface of the insulating materia 48.

According to our invention, at the rear of this air circulating space 46 we provide a forwardly directed inlet air opening 50 having an air scoop 51 beneath it in the downwardly directed discharge outlet 52 of the centrifugal fan 54. This centrifugal fan 54 is driven by the electric motor 56 and has an inlet shroud 58 extending over an aperture 60 located in the rear of the false bottom wall 34 communicating with the rear space 62 of the horizontal duct in the wall 22 behind the evaporator 38. The centrifugal fan 54 also has an upwardly directed discharge duct 64 provided with a deflector 66 for discharging a majority of the air drawn from the rear space 62 in a distributed manner into the upper sub-compartment 24. The downwardly directed discharge outlet 52, in addition to discharging a small amount of air through the discharge inlet Sii into the air circulating space 46, also discharges a substantial amount of air through its lower discharge outlet 68 upon the rear wall 70 of the compartment 26. The cold air discharged through the upper and lower discharge ducts 64 and 68 into the subcompartments 24 and 26 is sufiicient to keep these compartments at the desired temperatures.

The air discharged through the inlet 50 provides a forward air circulation in the air circulating space 46 beneath the drain pan 32 which prevents any moisture from collecting and freezing thereon. The air circulating space 46 at the front is provided with an outlet opening 72 from which the air discharges into the space 44 in front of the evaporator 38. The evaporator 38 is provided with an electirc defrost heater 74 upon its lower surface in contact with the upper surface of the drain pan 32. This defrost heater 74 is energized while the fan 54 and the refrigerating system are idle to melt frost from the evaporator 38 and from the upper surface of the drain pan 32 at suitable intervals. The drain pan 32 is provided with a sump 76 discharging through the drain troughs '78 to a down spout 80 in the rear wall 70. This down spout 80 discharges through an aperture 82 into the bottom of the compartment 26 which is drained through an outlet 84.

By the provision of the air circulating space 46 and the provision for positive air circulation through it from the inlet 50, there is no necessity for providing any covering for the upper surface of the insulation 48. The lower surface of the insulation 48 has bonded to its lower surface a thin sheet of metal as which effectively prevents the infiltration of moisture from the compartment 22. Thus, through this arrangement, the insulation 48 is kept dry and at its maximum insulating efliciency.

While the embodiments of the present invention as herein disclosed, constitute preferred forms, it is to be understood that the other forms might be adopted.

What is claimed is as follows:

1. A refrigerator including insulating means enclosing a compartment to be cooled, means forming a duct communicating with said compartment, said duct having a bottom wall surface, a refrigerant evaporating means located in said duct, a drain pan within said duct beneath said evaporating means spaced above the bottom wall surface of said duct to provide an air circulating space between said pan and bottom wall surface, fan means for circulating air from said compartment through said duct into heat transfer with said evaporating means and returning the air to said compartment, and means for directing a portion of. said circulating air through said air circulating space beneath said drain pan.

2. A refrigerator as defined in claim 1 in which said fan means has a fan outlet means and said means for directing a portion of said circulating air comprises a discharge opening in said fan outlet means discharging into said air circulating space beneath said drain pan.

3. A refrigerator as defined in claim 1 in which said means for directing a portion of said circulating air is provided by separate openings in said duct located on opposite sides of said evaporating means communicating with spaced points within said air circulating space.

4. A refrigerator as defined in claim 1 in which said means for directing a portion of said circulating air is provided by separate openings in said duct located on opposite sides of said fan means communicating with spaced points within said air circulating space.

5. A refrigerator as defined in claim 1 in which said fan means has an inlet communicating through said duct with said evaporating means and has an outlet communicating with said compartment to be cooled, said air circulating space having one portion communicating with said outlet of said fan means to receive a portion of said circulating air.

6. A refrigerator as defined in claim 1 in which said duct extends within an insulated horizontal wall adjoining said compartment and has an opening at the front communicating with said compartment, and in which said fan means is located at the rear and communicates with said duct and said compartment, said means forming said duct having an opening at the front communicating with said air circulating space and an opening at the rear communicating with said air circulating space.

7. A refrigerator as defined in claim 1 in which said duct extends within an insulated horizontal wall dividing said compartment into upper and lower sub-compartments to be cooled, said means forming said duct having an opening at the front and an opening at the rear communicating with the front and rear of said air circulating space and each of said sub-compartments.

8. A refrigerator as defined in claim 1 in which said duct extends within an insulated horizontal wall dividing said compartment into upper and lower sub-compartments to be cooled, said means forming said duct having an opening at the front and an opening at the rear communicating with the front and rear of said air circulating space and each of said sub-compartments, said last named means also having a tongue adjacent the opening at the front for directing air from the upper and lower subcompartments into the upper and lower portions of said duct.

References Cited by the Examiner UNITED STATES PATENTS 2,515,892 7/1950 Philipp 62-273 2,595,874 5/1952 Nason 62 273 2,761,290 9/1956 Philipp 62-273 WILLIAM J. WYE, Primary Examiner. 

1. A REFRIGERATOR INCLUDING INSULATING MEANS ENCLOSING A COMPARTMENT TO BE COOLED, MEANS FORMING A DUCT COMMUNICATING WITH SAID COMPARTMENT, SAID DUCT HAVING A BOTTOM WALL SURFACE, A REFRIGERANT EVAPORATING MEANS LOCATED IN SAID DUCT, A DRAIN PAN WITHIN SAID DUCT BEING SAID EVAPORATING MEANS SPACED ABOVE THE BOTTOM WALL SURFACE OF SAID DUCT TO PROVIDE AN AIR CIRCULATING SPACE BETWEEN SAID PAN AND BOTTOM WALL SURFACE, FAN MEANS FOR 